Event-recording cardio-respiratory monitors may add a significant new technology for the management of infant apnea. The appropriate use of these monitors has yet to be defined. The goals of this study are to (1) determine the frequency, duration, and type of respiratory and cardiac patterns seen in infants at risk for a life threatening event, (2) determine patient compliance with home monitoring, and (3) obtain information on the physiologic and clinical significance of recorded alarm events. In addition, we will test the hypotheses: (1) recording of events by an event-recording monitor results in better management of infants than parental reporting of alarms, (2) event-recording monitors detect all events seen within polysomnographic studies, (3) obstructive apnea is seen in infants at risk for SIDS, and (4) event-recording monitors will provide better data to determine when monitoring can be discontinued. Biophysical and demographic data will be collected from a sample of infants in the following risk groups: (1) former premature infants, (2) subsequent siblings of infants who died of SIDS, and (3) infants who have experienced an acute life threatening event (ALTE). All infants will receive event-recording home monitors including a pulse oximeter, and subjects will be randomized into two equal groups: those who's caregivers will report events based only on monitor alarms, and those who will provide their physician with full access to recorded events. The protocol will determine whether there is a difference in the outcome measures of: (1) SIDS, (2) ALTE, (3) further medical intervention required, (4) age when monitor is discontinued, and (5) relapse. Infants will be monitored at home for approximately 6 months and have regular return visits for repeat polysomnographic studies. The usefulness of these polysomnograms will be evaluated by comparing the results of these tests with the outcome measures. Recorded events from the monitors will be analyzed to determine if those infants with one of more positive outcome measures display different patterns of events from normals. Home monitoring devices will be used during the in-hospital polysomnographic studies to determine the sensitivity and specificity of the event detection algorithm, and the false alarm rate will be determined from the event recordings. Special instrumentation used for testing monitors and evaluating obstructive apnea will be developed in conjunction with the NCRR supported CWRU Resource on Biomedical Sensor Technology.